Gervais' Beaked Whale (Mesoplodon europaeus)

Gervais' Beaked Whale
(Mesoplodon europaeus)
Photo: NMFS Southeast Fisheries Science Center

Did You Know?

· Gervais' beaked whales may be the most commonly sighted species of Mesoplodont off the U.S. Atlantic coast and the Gulf of Mexico.

· Gervais' beaked whales are the most common species of the genus Mesoplodon to strand on the U.S. southeastern Atlantic coast.

Status
MMPA - Gervais' beaked whales, like all marine mammals, are protected under the MMPA.

Taxonomy
Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Order: Cetacea
Family: Ziphiidae
Genus: Mesoplodon
Species: europaeus

Species Description

Gervais' beaked whales, sometimes called the "Antillean" or "Gulf Stream beaked whale," are little known members of the beaked whale family (Ziphiidae) (Reeves et al. 2002). As adults, Gervais' beaked whales can reach estimated lengths of about 15-17 ft (4.6-5.2 m) and weigh at least 2,640 lbs (1200 kg). Females may be slightly larger than males. Males can be distinguished from females and juveniles by a pair of visible teeth that erupt from the front portion of the bottom jaw. Females and juveniles have teeth as well, but they remain hidden beneath the gum tissue of the mouth. The jawline is typically straight or slightly curved.

Gervais' beaked whales have a relatively small to medium size body with a moderately long beak and an indistinct sloping "melon". They have a small, triangular, wide-based, slightly "falcate", "dorsal" fin located far down (about two-thirds) the animal's back. The coloration of the body is dark gray or bluish to black with a paler ventral side. Animals tend to become darker as they age. Mature males may also have linear scars from battles over females. This species of beaked whale is difficult to observe and identify at sea due to a low profile at the surface and a small, inconspicuous blow.

Many species of beaked whales (especially those in the genus Mesoplodon) are very difficult to distinguish from one another (even when dead). At sea, they are challenging to observe and identify to the species level due to their cryptic, skittish behavior, a low profile, and a small, inconspicuous blow at the waters surface; therefore, much of the available characterization for beaked whales is to genus level only. Uncertainty regarding species identification of beaked whales often exists because of a lack of easily discernable or distinct physical characteristics.

Gervais' beaked whales are usually found individually or in small closely associated social groups. While diving, they use suction to feed mainly on cephalopods (e.g., squid), mysid shrimp, and small fish in deep water.

Females may become sexually mature at 15 ft (4.5 m). A sexually mature female will give birth to a single newborn calf that is about 7 ft (1.6-2.2 m) long and weighs about 176 lbs (80 kg). The estimated lifespan of this species is at least 27 years, but may be up to 48 years (Reeves et al. 2002).

Habitat
Gervais' beaked whales prefer deep tropical, subtropical, and warm temperate waters of the Atlantic Ocean, but are occasionally found in colder temperate seas.

Gervais' Beaked Whale Range Map
(click for larger view PDF)

Distribution
Gervais' beaked whales are distributed throughout deep, warm waters of the central and north Atlantic Ocean. This species is thought to occur mostly north of the equator. Their range includes the English Channel, Europe, Canaries Islands, Western Africa, Brazil, Caribbean Sea, Gulf of Mexico, and the eastern north Atlantic (Jefferson et al. 2008). There are no known seasonal movements or migrations for this species.

Population Trends
For management purposes, Gervais' beaked whales inhabiting U.S. waters have been divided into the Western North Atlantic stock and the Northern Gulf of Mexico stock. The estimated population for Mesoplodon spp. (Blainville's and Gervais' beaked whales) in the Northern Gulf of Mexico is 75-100 animals. This stock is considered "strategic" due to the uncertainty surrounding its status. No current population estimates are available for the Western North Atlantic stock of this species of beaked whale, but based on the number of strandings, they may be fairly common along the U.S. Atlantic coast. There are insufficient data to determine the population trends for this species.

Threats
Gervais' beaked whales have been incidentally taken as bycatch in fishing gear, such as pound nets off the U.S. Atlantic coast and potentially in driftnets and gillnets. This species may be captured in the Caribbean Sea for food. This species of beaked whale may be sensitive to underwater sounds and anthropogenic noise. Anthropogenic noise levels in the world's oceans are an increasing habitat concern, particularly for deep-diving cetaceans like Gervais' beaked whales that use sound to feed, communicate, and navigate in the ocean.

Conservation Efforts
The International Union for Conservation of Nature (IUCN's) Red List of Threatened Species considers this species "Data Deficient" due to insufficient information on population status and trends.

Regulatory Overview
This species is protected under the Marine Mammal Protection Act of 1972, as amended.

Key Documents
(All documents are in PDF format.)

Title	Federal Register	Date
Stock Assessment Reports	n/a	various

More Information

References:

Reeves, R. R., P. A. Folkens, et al. (2002). Guide to Marine Mammals of the World. New York, Alfred A. Knopf. p. 278-279.
Jefferson, T. A, M. A. Webber, and R. L. Pitman. (2008). Marine Mammals of the World, A Comprehensive Guide to their Identification. Amsterdam, Elsevier. p. 132-134.
Shirihai, H. and B. Jarrett (2006). Whales, Dolphins and Other Marine Mammals of the World. Princeton, Princeton University Press. p. 127-129.